Sales and marketing of mechanical seals presently involves several activities including seal selection, design and engineering of a seal, manufacturing, and post sales service and support. This process involves many different people to gather, manipulate, interpret and process a variety of kinds of information, and is not an exact science.
A mechanical seal is a shaft sealing device provided to contain process fluids within equipment such as a pump, mixer or other rotary equipment. Mechanical seals are used in operations of a typical processing plant. Significant industries that use seals include: pulp and paper, chemical processing, petroleum chemical, oil refining, food, processing, and power and utilities, among others.
There are generally three types of mechanical seals: component (made of several pieces), cartridge (components unitized for one piece) and split seals. Cartridge seals generally are preferred over component seals for several reasons. First, cartridge seals may be installed without significant training. These seals also may be tested before shipping to ensure sealability. However, conversion from a component seal to a cartridge seal for an application involves a complex process of selection of an appropriate seal design.
Because of the variety of applications for seals, selection of a seal involves considering several factors. For example, seals typically are connected to equipment with a rotary shaft (pumps being the most common) for which there are a large variety of commercially available designs with different dimensional profiles. Equipment also may have been modified in the field for several reasons, resulting in a nonstandard dimensional profile. Additional factors are the operating conditions of the equipment, including process fluids and their combinations, and intentional and unintentional changes in the process fluids used in a systems. Aside from selecting a seal that fits the equipment and is suitable for the given operating conditions, costs of the seal and its installation also are factors.
This selection process therefore generally involves highly trained sales engineers with factory support to perform properly the seal selection process. Their training typically includes mechanical and design engineering and chemical engineering. These individuals typically also perform sales, service and support functions. Because of the complexity of the seal selection process, customers tend to be dependent on these sales engineers. This dependency is due to the complexity of part codes for these seals.
The expertise level of a sales engineer is generally dependent on the size of seal manufacturer, years of experience, education and training, resulting in varying competencies. Sales engineers may possess only industry specific expertise, acquired from their experience. Accordingly, without extensive experience, a sales engineer also may be dependent heavily on factory support for assistance in the seal selection process.
Moreover, sales engineers, despite their experience, still may be dependent on factory support because they typically have immediate access to selection information limited to common equipment and process fluids, either in printed or computer-readable text form. Other information, such as application data, engineering data, special pricing and drawings may be available only at the factory, requiring the sales engineer to use factory support to derive seal selections or to interpret the available information and to select a seal. Accurate communication between sales engineers and factory engineers is a critical component of this process.
Depending on the resources available to a manufacturer, which may depend on its size or its number of years in business, factory support may be limited to manually intensive selection methods prone to errors resulting in an informal, unscientific selection process. Even with more sophisticated procedures based on significant amounts of historical information, however, human intervention is generally required for many decisions made between field sales and factory support personnel because of individuals' judgments and perceptions, which may result in inaccurate selections. In particular, a significant amount of human interaction is required to gather, interpret, manipulate and analyze the application data when the sales engineer requires factory support. In particular, the pump and seal dimensions, operating conditions and process fluids affect the selection of materials to obtain maximum seal life. The human interaction involved in current selection methods may result in different recommendations from different individuals, for the same application, of a seal model, optional seal features, materials of construction, seal environmental controls, i.e., piping plans, and various auxiliary devices to be used with the environmental controls. In addition, the likelihood of an error is increased. An error in any stage of the selection process may result in an inaccurate or incomplete sealing solution, which translates into premature seal failure and increased costs.
There are several steps in the seal selection process which typically involve human interaction. One step is identification of the equipment, e.g., a pump or drive motor or other rotary equipment. The methods of identification differ among sales engineers. Example sources of identification information include identification tags on the equipment, maintenance records, engineering records, purchasing records, equipment manufacturer's records or seal manufacturer's records. If these sources provide incomplete information proper equipment identification may be impossible. Even if equipment is properly identified, e.g., by make and model, modifications may have been made to the equipment. A failure to identify such modifications results in an erroneous seal selection. As a result, a trained individual measures the equipment to obtain accurate dimensional data. Dimensional data is commonly collected using forms of varying complexity and completeness. Simple forms tend to be incomplete. Complex forms tend to be subject to interpretation by sales engineers and factory engineers. Both kinds of forms result in errors.
A seal model which is dimensionally compatible for the identified equipment then is selected. In order to make this selection, a sales engineer may refer to information available in a reference guide, or if not identified in a reference guide, performs a dimensional analysis. The dimensional analysis may be performed by the sales engineer or by relying upon factory support. When application data is received at the factory, it is reviewed for completeness and accuracy. If the data is not satisfactory, the process is delayed.
After a dimensionally compatible seal model has been selected, the operating conditions are identified by the sales engineer and are analyzed to confirm that the recommended seal is suitable for the process performed by the equipment. This analysis involves evaluating the operating conditions and the process fluids, with respect to a number of aspects of the seal, including, but not limited to: a metallurgy for general corrosion resistance; a face material combination for lubricity of the chemical and/or corrosion or abrasion resistance; and selection of secondary sealing components, i.e., o-ring elastomers for temperature and chemical resistance.
The operation conditions include but are not limited to: shaft speed as related to seal chamber pressure acting on the seal, i.e., pressure/velocity; stuffing box/seal chamber pressure, which is a function, of different pump internal part designs (impellers); shaft speed; pump discharge pressure at outlet nozzle; pump suction pressure at inlet nozzle; pressure/velocity parameters for different seal designs and face material combinations; box pressure calculations based on pump design type; seal face balance design; concentration; temperature; viscosity; the percentage of undissolved or dissolved or fibrous or nonfibrous solids; vapor pressure; specific gravity; and pollutants and other chemicals. Sometimes these values are estimated or are not obtained.
Either the sales engineer or factory support may analyze the operating conditions, depending on experience and resources. The parameter limits for various operating conditions generally are maintained in printed engineering tables by seal type, or may be calculated. If this analysis is performed by untrained individuals using only printed tables and without an engineering level analysis, or if incomplete information is used, then the analysis may be inaccurate or erroneous. It may also be inappropriate to select the material of a previous seal.
If the analysis indicates that a standard seal model is not acceptable, appropriate modifications to either a seal or the equipment are determined. An engineer may have a limited information guide explaining the modifications to be made to popular pumps to fit popular seals. Modifications to a seal generally are not provided. Otherwise the modifications are determined, either by the sales engineer or factory support, by reference to various guides or by analysis or based on historical information such as previous bills of material and factory engineering drawings. If the information used to make the modifications is inaccurate or incomplete, an inappropriate modification may be made to the seal or the equipment.
The process fluids also are analyzed to review characteristics which may affect seal selection, such as, but not limited to: volatile hazardous air pollutants, which requires selection of a double seal for absolute zero vapor emission leakage; flammability; toxicity; polymerization; solidification; abrasive slurries; percentage concentration of primary and secondary chemicals; and minimum and maximum process temperatures.
If a sales engineer has a reference guide with material ratings for a seal, the final seal selection is made by the sales engineer based on training and experience. A reference guide also may indicate materials for use with only one process chemical, without consideration of secondary chemicals which may be present in the process. If the guide is not complete, factory support may be required for assistance. An engineer providing factory support analyzes the process to identify the process fluid chemical characteristics, for example by utilizing published technical reference sources, chemical dictionaries, or historical information such as previous bills of material, or by basing a selection on properties of a chemical with similar characteristics. As with other steps involving factory support, information may be missing from the sales engineer, thus incurring a delay or resulting in an incorrect selection. Because of the complexity of the process fluid analysis, errors in selection are possible.
The sales engineer also selects optional seal features to obtain optimum seal performance life. Such features include, but are not limited to: a two piece stationary face (for viscous or polymerizing chemicals); a quench and drain gland (to cool or heat seal faces, or wash away crystalline deposits on atmospheric side of the seal faces); and pumping sleeves for double seals to provide maximum flow of barrier fluid to cool and lubricate the seal faces. The limited information on optional features in a reference guide may be limited. Otherwise, sales engineers derive the selection of optional features from the chemical characteristics. Whether a given seal has optional features to handle the application may require factory support for a recommendation.
Another step of the seal selection process is determining the best environmental controls or American Petroleum Institute (API) standard plan. The environmental controls are systems used to cool, lubricate, heat, etc., thereby controlling the environment of the mechanical seal, particularly at the seal faces. For an existing application, the sales engineer identifies the current external piping system and evaluates whether it should be modified for the application. For a new application, the sales engineer identifies piping systems available. A limited reference guide may help derive selection of the piping plan or factory support may be required. This aspect of the selection process may even be neglected or an existing piping plan may be incorrect for the application, thereby resulting in premature seal failure. Significant interaction between customers, sales engineers, and factory engineers may be required for proper selection.
Another step of the seal selection process is the selection of a variety of auxiliary devices, i.e., products external to the seal and typically in the piping plan, including but not limited to: supply tanks for double seal piping systems; throat bushings for use with external clean flush systems to seal faces; and flow control devices for external flush systems for single seals and double seals. As with other aspects of this process, such devices may be selected using limited reference guides, or application engineers may calculate the design, size and selection of an auxiliary device. Depending on the type of auxiliary, e.g., throat bushings, equipment dimensions may be needed by an engineer to design and manufacture the device.
After a seal with appropriate materials and optional features, environmental controls and auxiliaries have been selected, an appropriate price is determined along with a bill of materials and specifications for installation. Current pricing methods for mechanical seals for standard products typically involves price lists or books. The pricing book may be complex and may require factory support to be interpreted in order to arrive at a price for a given seal selection. When special designs are made, a selling price and discount structure is more complex to determine, and typically involves trained engineers and accountants. The entire quotation process involves time frames ranging from days to weeks.
Ultimately, after quotation and receipt of an order, a seal is manufactured according to the quotation if the seal is not a standard part. Manufacturing operations vary based on the size and scope of products offered by a seal manufacturer and the manufacturing process technologies used. The kinds of manufacturing equipment used ranges from manual equipment to computer numerically controlled (CNC) equipment in various combinations depending on the scope of products and raw materials for the products. Despite the size of the manufacturer, highly trained individuals typically are needed for manufacturing.
While some manufacturers may use a computer program to assist in seal selection, such computer programs are generally an automated look-up table with which a user selects a model number of a pump, a corresponding product line of seals and receives a selection of possible seals. In some cases, the user may even select the materials for the seals. Such tools generally require either mechanical or chemical engineering knowledge or a significant amount of experience in order to select a seal correctly.
In sum, because of the complexity of the seal selection process, manufacturing and marketing of mechanical seals requires seal manufacturers to be dependent upon highly trained individuals. Customers depend on sales engineers and the manufacturer for technical support in order to obtain accurate solutions to field service problems. Because of complexity, delay and cost of the seal selection process, a customer may replace a failed seal with a seal of the same type rather than make a corrective selection. Premature seal failure may continue to occur, resulting in excessive operating costs.
The combination of the complexities and requirements of seal selection, quotation, design and engineering, manufacturing and post sales support processes thus produces inconsistent, unscientific and erroneous results, and increased costs.